Get as fit and strong as possible over the next two years then join. If you can join the cadets for two years it will massively help you in training also
Long distance ruck marching will be important which is for all intents and purposes very brisk walking with a bergen. Start slowly and work your way up. It is surprisingly easy to give yourself an injury merely walking under load even on flat terrain, even something really minor can cascade into other things if you don't have the time or means to get it sorted. During training and in the role you will at times have to run with a lot of weight on you. It's very easy to get injured doing this if you don't know what you're doing so keep that in mind. Definitely practice running and rucking but be mindful of combining, perhaps even waiting until you're older, stronger and more experienced. Practice hills and get used to wearing boots. Running around in boots is a lot harder than sneakers. Blisters aren't a joke either. They're not simply about manning up through pain. If let, they get worse, affecting your gait and weight distribution leading to all kinds of kinetic chain risks.
